#include "lci_slam/vilens/camera/camera_model/gpl.h"

#include <set>
#ifdef _WIN32
#include <winsock.h>
#else
#include <time.h>
#endif

// source:
// https://stackoverflow.com/questions/5167269/clock-gettime-alternative-in-mac-os-x
#ifdef __APPLE__
#include <mach/mach_time.h>
#define ORWL_NANO (+1.0E-9)
#define ORWL_GIGA UINT64_C(1000000000)

static double orwl_timebase = 0.0;
static uint64_t orwl_timestart = 0;

struct timespec orwl_gettime(void) {
    // be more careful in a multithreaded environement
    if (!orwl_timestart) {
        mach_timebase_info_data_t tb = {0};
        mach_timebase_info(&tb);
        orwl_timebase = tb.numer;
        orwl_timebase /= tb.denom;
        orwl_timestart = mach_absolute_time();
    }
    struct timespec t;
    double diff = (mach_absolute_time() - orwl_timestart) * orwl_timebase;
    t.tv_sec = diff * ORWL_NANO;
    t.tv_nsec = diff - (t.tv_sec * ORWL_GIGA);
    return t;
}
#endif  // __APPLE__

const double WGS84_A = 6378137.0;
const double WGS84_ECCSQ = 0.00669437999013;

// Windows lacks fminf
#ifndef fminf
#define fminf(x, y) (((x) < (y)) ? (x) : (y))
#endif

namespace camodocal {

double hypot3(double x, double y, double z) {
    return sqrt(square(x) + square(y) + square(z));
}

float hypot3f(float x, float y, float z) {
    return sqrtf(square(x) + square(y) + square(z));
}

double d2r(double deg) { return deg / 180.0 * M_PI; }

float d2r(float deg) { return deg / 180.0f * M_PI; }

double r2d(double rad) { return rad / M_PI * 180.0; }

float r2d(float rad) { return rad / M_PI * 180.0f; }

double sinc(double theta) { return sin(theta) / theta; }

#ifdef _WIN32
#include <sys/timeb.h>
#include <sys/types.h>
#include <winsock.h>
LARGE_INTEGER
getFILETIMEoffset() {
    SYSTEMTIME s;
    FILETIME f;
    LARGE_INTEGER t;

    s.wYear = 1970;
    s.wMonth = 1;
    s.wDay = 1;
    s.wHour = 0;
    s.wMinute = 0;
    s.wSecond = 0;
    s.wMilliseconds = 0;
    SystemTimeToFileTime(&s, &f);
    t.QuadPart = f.dwHighDateTime;
    t.QuadPart <<= 32;
    t.QuadPart |= f.dwLowDateTime;
    return (t);
}

int clock_gettime(int X, struct timespec* tp) {
    LARGE_INTEGER t;
    FILETIME f;
    double microseconds;
    static LARGE_INTEGER offset;
    static double frequencyToMicroseconds;
    static int initialized = 0;
    static BOOL usePerformanceCounter = 0;

    if (!initialized) {
        LARGE_INTEGER performanceFrequency;
        initialized = 1;
        usePerformanceCounter =
            QueryPerformanceFrequency(&performanceFrequency);
        if (usePerformanceCounter) {
            QueryPerformanceCounter(&offset);
            frequencyToMicroseconds =
                (double)performanceFrequency.QuadPart / 1000000.;
        } else {
            offset = getFILETIMEoffset();
            frequencyToMicroseconds = 10.;
        }
    }
    if (usePerformanceCounter)
        QueryPerformanceCounter(&t);
    else {
        GetSystemTimeAsFileTime(&f);
        t.QuadPart = f.dwHighDateTime;
        t.QuadPart <<= 32;
        t.QuadPart |= f.dwLowDateTime;
    }

    t.QuadPart -= offset.QuadPart;
    microseconds = (double)t.QuadPart / frequencyToMicroseconds;
    t.QuadPart = microseconds;
    tp->tv_sec = t.QuadPart / 1000000;
    tp->tv_nsec = (t.QuadPart % 1000000) * 1000;
    return (0);
}
#endif

unsigned long long timeInMicroseconds(void) {
    struct timespec tp;
#ifdef __APPLE__
    tp = orwl_gettime();
#else
    clock_gettime(CLOCK_REALTIME, &tp);
#endif

    return tp.tv_sec * 1000000 + tp.tv_nsec / 1000;
}

double timeInSeconds(void) {
    struct timespec tp;
#ifdef __APPLE__
    tp = orwl_gettime();
#else
    clock_gettime(CLOCK_REALTIME, &tp);
#endif

    return static_cast<double>(tp.tv_sec) +
           static_cast<double>(tp.tv_nsec) / 1000000000.0;
}

float colormapAutumn[128][3] = {
    {1.0f, 0.f, 0.f},       {1.0f, 0.007874f, 0.f}, {1.0f, 0.015748f, 0.f},
    {1.0f, 0.023622f, 0.f}, {1.0f, 0.031496f, 0.f}, {1.0f, 0.03937f, 0.f},
    {1.0f, 0.047244f, 0.f}, {1.0f, 0.055118f, 0.f}, {1.0f, 0.062992f, 0.f},
    {1.0f, 0.070866f, 0.f}, {1.0f, 0.07874f, 0.f},  {1.0f, 0.086614f, 0.f},
    {1.0f, 0.094488f, 0.f}, {1.0f, 0.10236f, 0.f},  {1.0f, 0.11024f, 0.f},
    {1.0f, 0.11811f, 0.f},  {1.0f, 0.12598f, 0.f},  {1.0f, 0.13386f, 0.f},
    {1.0f, 0.14173f, 0.f},  {1.0f, 0.14961f, 0.f},  {1.0f, 0.15748f, 0.f},
    {1.0f, 0.16535f, 0.f},  {1.0f, 0.17323f, 0.f},  {1.0f, 0.1811f, 0.f},
    {1.0f, 0.18898f, 0.f},  {1.0f, 0.19685f, 0.f},  {1.0f, 0.20472f, 0.f},
    {1.0f, 0.2126f, 0.f},   {1.0f, 0.22047f, 0.f},  {1.0f, 0.22835f, 0.f},
    {1.0f, 0.23622f, 0.f},  {1.0f, 0.24409f, 0.f},  {1.0f, 0.25197f, 0.f},
    {1.0f, 0.25984f, 0.f},  {1.0f, 0.26772f, 0.f},  {1.0f, 0.27559f, 0.f},
    {1.0f, 0.28346f, 0.f},  {1.0f, 0.29134f, 0.f},  {1.0f, 0.29921f, 0.f},
    {1.0f, 0.30709f, 0.f},  {1.0f, 0.31496f, 0.f},  {1.0f, 0.32283f, 0.f},
    {1.0f, 0.33071f, 0.f},  {1.0f, 0.33858f, 0.f},  {1.0f, 0.34646f, 0.f},
    {1.0f, 0.35433f, 0.f},  {1.0f, 0.3622f, 0.f},   {1.0f, 0.37008f, 0.f},
    {1.0f, 0.37795f, 0.f},  {1.0f, 0.38583f, 0.f},  {1.0f, 0.3937f, 0.f},
    {1.0f, 0.40157f, 0.f},  {1.0f, 0.40945f, 0.f},  {1.0f, 0.41732f, 0.f},
    {1.0f, 0.4252f, 0.f},   {1.0f, 0.43307f, 0.f},  {1.0f, 0.44094f, 0.f},
    {1.0f, 0.44882f, 0.f},  {1.0f, 0.45669f, 0.f},  {1.0f, 0.46457f, 0.f},
    {1.0f, 0.47244f, 0.f},  {1.0f, 0.48031f, 0.f},  {1.0f, 0.48819f, 0.f},
    {1.0f, 0.49606f, 0.f},  {1.0f, 0.50394f, 0.f},  {1.0f, 0.51181f, 0.f},
    {1.0f, 0.51969f, 0.f},  {1.0f, 0.52756f, 0.f},  {1.0f, 0.53543f, 0.f},
    {1.0f, 0.54331f, 0.f},  {1.0f, 0.55118f, 0.f},  {1.0f, 0.55906f, 0.f},
    {1.0f, 0.56693f, 0.f},  {1.0f, 0.5748f, 0.f},   {1.0f, 0.58268f, 0.f},
    {1.0f, 0.59055f, 0.f},  {1.0f, 0.59843f, 0.f},  {1.0f, 0.6063f, 0.f},
    {1.0f, 0.61417f, 0.f},  {1.0f, 0.62205f, 0.f},  {1.0f, 0.62992f, 0.f},
    {1.0f, 0.6378f, 0.f},   {1.0f, 0.64567f, 0.f},  {1.0f, 0.65354f, 0.f},
    {1.0f, 0.66142f, 0.f},  {1.0f, 0.66929f, 0.f},  {1.0f, 0.67717f, 0.f},
    {1.0f, 0.68504f, 0.f},  {1.0f, 0.69291f, 0.f},  {1.0f, 0.70079f, 0.f},
    {1.0f, 0.70866f, 0.f},  {1.0f, 0.71654f, 0.f},  {1.0f, 0.72441f, 0.f},
    {1.0f, 0.73228f, 0.f},  {1.0f, 0.74016f, 0.f},  {1.0f, 0.74803f, 0.f},
    {1.0f, 0.75591f, 0.f},  {1.0f, 0.76378f, 0.f},  {1.0f, 0.77165f, 0.f},
    {1.0f, 0.77953f, 0.f},  {1.0f, 0.7874f, 0.f},   {1.0f, 0.79528f, 0.f},
    {1.0f, 0.80315f, 0.f},  {1.0f, 0.81102f, 0.f},  {1.0f, 0.8189f, 0.f},
    {1.0f, 0.82677f, 0.f},  {1.0f, 0.83465f, 0.f},  {1.0f, 0.84252f, 0.f},
    {1.0f, 0.85039f, 0.f},  {1.0f, 0.85827f, 0.f},  {1.0f, 0.86614f, 0.f},
    {1.0f, 0.87402f, 0.f},  {1.0f, 0.88189f, 0.f},  {1.0f, 0.88976f, 0.f},
    {1.0f, 0.89764f, 0.f},  {1.0f, 0.90551f, 0.f},  {1.0f, 0.91339f, 0.f},
    {1.0f, 0.92126f, 0.f},  {1.0f, 0.92913f, 0.f},  {1.0f, 0.93701f, 0.f},
    {1.0f, 0.94488f, 0.f},  {1.0f, 0.95276f, 0.f},  {1.0f, 0.96063f, 0.f},
    {1.0f, 0.9685f, 0.f},   {1.0f, 0.97638f, 0.f},  {1.0f, 0.98425f, 0.f},
    {1.0f, 0.99213f, 0.f},  {1.0f, 1.0f, 0.0f}};

float colormapJet[128][3] = {
    {0.0f, 0.0f, 0.53125f},     {0.0f, 0.0f, 0.5625f},
    {0.0f, 0.0f, 0.59375f},     {0.0f, 0.0f, 0.625f},
    {0.0f, 0.0f, 0.65625f},     {0.0f, 0.0f, 0.6875f},
    {0.0f, 0.0f, 0.71875f},     {0.0f, 0.0f, 0.75f},
    {0.0f, 0.0f, 0.78125f},     {0.0f, 0.0f, 0.8125f},
    {0.0f, 0.0f, 0.84375f},     {0.0f, 0.0f, 0.875f},
    {0.0f, 0.0f, 0.90625f},     {0.0f, 0.0f, 0.9375f},
    {0.0f, 0.0f, 0.96875f},     {0.0f, 0.0f, 1.0f},
    {0.0f, 0.03125f, 1.0f},     {0.0f, 0.0625f, 1.0f},
    {0.0f, 0.09375f, 1.0f},     {0.0f, 0.125f, 1.0f},
    {0.0f, 0.15625f, 1.0f},     {0.0f, 0.1875f, 1.0f},
    {0.0f, 0.21875f, 1.0f},     {0.0f, 0.25f, 1.0f},
    {0.0f, 0.28125f, 1.0f},     {0.0f, 0.3125f, 1.0f},
    {0.0f, 0.34375f, 1.0f},     {0.0f, 0.375f, 1.0f},
    {0.0f, 0.40625f, 1.0f},     {0.0f, 0.4375f, 1.0f},
    {0.0f, 0.46875f, 1.0f},     {0.0f, 0.5f, 1.0f},
    {0.0f, 0.53125f, 1.0f},     {0.0f, 0.5625f, 1.0f},
    {0.0f, 0.59375f, 1.0f},     {0.0f, 0.625f, 1.0f},
    {0.0f, 0.65625f, 1.0f},     {0.0f, 0.6875f, 1.0f},
    {0.0f, 0.71875f, 1.0f},     {0.0f, 0.75f, 1.0f},
    {0.0f, 0.78125f, 1.0f},     {0.0f, 0.8125f, 1.0f},
    {0.0f, 0.84375f, 1.0f},     {0.0f, 0.875f, 1.0f},
    {0.0f, 0.90625f, 1.0f},     {0.0f, 0.9375f, 1.0f},
    {0.0f, 0.96875f, 1.0f},     {0.0f, 1.0f, 1.0f},
    {0.03125f, 1.0f, 0.96875f}, {0.0625f, 1.0f, 0.9375f},
    {0.09375f, 1.0f, 0.90625f}, {0.125f, 1.0f, 0.875f},
    {0.15625f, 1.0f, 0.84375f}, {0.1875f, 1.0f, 0.8125f},
    {0.21875f, 1.0f, 0.78125f}, {0.25f, 1.0f, 0.75f},
    {0.28125f, 1.0f, 0.71875f}, {0.3125f, 1.0f, 0.6875f},
    {0.34375f, 1.0f, 0.65625f}, {0.375f, 1.0f, 0.625f},
    {0.40625f, 1.0f, 0.59375f}, {0.4375f, 1.0f, 0.5625f},
    {0.46875f, 1.0f, 0.53125f}, {0.5f, 1.0f, 0.5f},
    {0.53125f, 1.0f, 0.46875f}, {0.5625f, 1.0f, 0.4375f},
    {0.59375f, 1.0f, 0.40625f}, {0.625f, 1.0f, 0.375f},
    {0.65625f, 1.0f, 0.34375f}, {0.6875f, 1.0f, 0.3125f},
    {0.71875f, 1.0f, 0.28125f}, {0.75f, 1.0f, 0.25f},
    {0.78125f, 1.0f, 0.21875f}, {0.8125f, 1.0f, 0.1875f},
    {0.84375f, 1.0f, 0.15625f}, {0.875f, 1.0f, 0.125f},
    {0.90625f, 1.0f, 0.09375f}, {0.9375f, 1.0f, 0.0625f},
    {0.96875f, 1.0f, 0.03125f}, {1.0f, 1.0f, 0.0f},
    {1.0f, 0.96875f, 0.0f},     {1.0f, 0.9375f, 0.0f},
    {1.0f, 0.90625f, 0.0f},     {1.0f, 0.875f, 0.0f},
    {1.0f, 0.84375f, 0.0f},     {1.0f, 0.8125f, 0.0f},
    {1.0f, 0.78125f, 0.0f},     {1.0f, 0.75f, 0.0f},
    {1.0f, 0.71875f, 0.0f},     {1.0f, 0.6875f, 0.0f},
    {1.0f, 0.65625f, 0.0f},     {1.0f, 0.625f, 0.0f},
    {1.0f, 0.59375f, 0.0f},     {1.0f, 0.5625f, 0.0f},
    {1.0f, 0.53125f, 0.0f},     {1.0f, 0.5f, 0.0f},
    {1.0f, 0.46875f, 0.0f},     {1.0f, 0.4375f, 0.0f},
    {1.0f, 0.40625f, 0.0f},     {1.0f, 0.375f, 0.0f},
    {1.0f, 0.34375f, 0.0f},     {1.0f, 0.3125f, 0.0f},
    {1.0f, 0.28125f, 0.0f},     {1.0f, 0.25f, 0.0f},
    {1.0f, 0.21875f, 0.0f},     {1.0f, 0.1875f, 0.0f},
    {1.0f, 0.15625f, 0.0f},     {1.0f, 0.125f, 0.0f},
    {1.0f, 0.09375f, 0.0f},     {1.0f, 0.0625f, 0.0f},
    {1.0f, 0.03125f, 0.0f},     {1.0f, 0.0f, 0.0f},
    {0.96875f, 0.0f, 0.0f},     {0.9375f, 0.0f, 0.0f},
    {0.90625f, 0.0f, 0.0f},     {0.875f, 0.0f, 0.0f},
    {0.84375f, 0.0f, 0.0f},     {0.8125f, 0.0f, 0.0f},
    {0.78125f, 0.0f, 0.0f},     {0.75f, 0.0f, 0.0f},
    {0.71875f, 0.0f, 0.0f},     {0.6875f, 0.0f, 0.0f},
    {0.65625f, 0.0f, 0.0f},     {0.625f, 0.0f, 0.0f},
    {0.59375f, 0.0f, 0.0f},     {0.5625f, 0.0f, 0.0f},
    {0.53125f, 0.0f, 0.0f},     {0.5f, 0.0f, 0.0f}};

void colorDepthImage(cv::Mat& imgDepth, cv::Mat& imgColoredDepth,
                     float minRange, float maxRange) {
    imgColoredDepth = cv::Mat::zeros(imgDepth.size(), CV_8UC3);

    for (int i = 0; i < imgColoredDepth.rows; ++i) {
        const float* depth = imgDepth.ptr<float>(i);
        unsigned char* pixel = imgColoredDepth.ptr<unsigned char>(i);
        for (int j = 0; j < imgColoredDepth.cols; ++j) {
            if (depth[j] != 0) {
                int idx = fminf(depth[j] - minRange, maxRange - minRange) /
                          (maxRange - minRange) * 127.0f;
                idx = 127 - idx;

                pixel[0] = colormapJet[idx][2] * 255.0f;
                pixel[1] = colormapJet[idx][1] * 255.0f;
                pixel[2] = colormapJet[idx][0] * 255.0f;
            }

            pixel += 3;
        }
    }
}

bool colormap(const std::string& name, unsigned char idx, float& r, float& g,
              float& b) {
    if (name.compare("jet") == 0) {
        float* color = colormapJet[idx];

        r = color[0];
        g = color[1];
        b = color[2];

        return true;
    } else if (name.compare("autumn") == 0) {
        float* color = colormapAutumn[idx];

        r = color[0];
        g = color[1];
        b = color[2];

        return true;
    }

    return false;
}

std::vector<cv::Point2i> bresLine(int x0, int y0, int x1, int y1) {
    // Bresenham's line algorithm
    // Find cells intersected by line between (x0,y0) and (x1,y1)

    std::vector<cv::Point2i> cells;

    int dx = std::abs(x1 - x0);
    int dy = std::abs(y1 - y0);

    int sx = (x0 < x1) ? 1 : -1;
    int sy = (y0 < y1) ? 1 : -1;

    int err = dx - dy;

    while (1) {
        cells.push_back(cv::Point2i(x0, y0));

        if (x0 == x1 && y0 == y1) {
            break;
        }

        int e2 = 2 * err;
        if (e2 > -dy) {
            err -= dy;
            x0 += sx;
        }
        if (e2 < dx) {
            err += dx;
            y0 += sy;
        }
    }

    return cells;
}

std::vector<cv::Point2i> bresCircle(int x0, int y0, int r) {
    // Bresenham's circle algorithm
    // Find cells intersected by circle with center (x0,y0) and radius r

    std::vector<std::vector<bool> > mask(2 * r + 1);

    for (int i = 0; i < 2 * r + 1; ++i) {
        mask[i].resize(2 * r + 1);
        for (int j = 0; j < 2 * r + 1; ++j) {
            mask[i][j] = false;
        }
    }

    int f = 1 - r;
    int ddF_x = 1;
    int ddF_y = -2 * r;
    int x = 0;
    int y = r;

    std::vector<cv::Point2i> line;

    line = bresLine(x0, y0 - r, x0, y0 + r);
    for (std::vector<cv::Point2i>::iterator it = line.begin(); it != line.end();
         ++it) {
        mask[it->x - x0 + r][it->y - y0 + r] = true;
    }

    line = bresLine(x0 - r, y0, x0 + r, y0);
    for (std::vector<cv::Point2i>::iterator it = line.begin(); it != line.end();
         ++it) {
        mask[it->x - x0 + r][it->y - y0 + r] = true;
    }

    while (x < y) {
        if (f >= 0) {
            y--;
            ddF_y += 2;
            f += ddF_y;
        }

        x++;
        ddF_x += 2;
        f += ddF_x;

        line = bresLine(x0 - x, y0 + y, x0 + x, y0 + y);
        for (std::vector<cv::Point2i>::iterator it = line.begin();
             it != line.end(); ++it) {
            mask[it->x - x0 + r][it->y - y0 + r] = true;
        }

        line = bresLine(x0 - x, y0 - y, x0 + x, y0 - y);
        for (std::vector<cv::Point2i>::iterator it = line.begin();
             it != line.end(); ++it) {
            mask[it->x - x0 + r][it->y - y0 + r] = true;
        }

        line = bresLine(x0 - y, y0 + x, x0 + y, y0 + x);
        for (std::vector<cv::Point2i>::iterator it = line.begin();
             it != line.end(); ++it) {
            mask[it->x - x0 + r][it->y - y0 + r] = true;
        }

        line = bresLine(x0 - y, y0 - x, x0 + y, y0 - x);
        for (std::vector<cv::Point2i>::iterator it = line.begin();
             it != line.end(); ++it) {
            mask[it->x - x0 + r][it->y - y0 + r] = true;
        }
    }

    std::vector<cv::Point2i> cells;
    for (int i = 0; i < 2 * r + 1; ++i) {
        for (int j = 0; j < 2 * r + 1; ++j) {
            if (mask[i][j]) {
                cells.push_back(cv::Point2i(i - r + x0, j - r + y0));
            }
        }
    }

    return cells;
}

void fitCircle(const std::vector<cv::Point2d>& points, double& centerX,
               double& centerY, double& radius) {
    // D. Umbach, and K. Jones, A Few Methods for Fitting Circles to Data,
    // IEEE Transactions on Instrumentation and Measurement, 2000
    // We use the modified least squares method.
    double sum_x = 0.0;
    double sum_y = 0.0;
    double sum_xx = 0.0;
    double sum_xy = 0.0;
    double sum_yy = 0.0;
    double sum_xxx = 0.0;
    double sum_xxy = 0.0;
    double sum_xyy = 0.0;
    double sum_yyy = 0.0;

    int n = points.size();
    for (int i = 0; i < n; ++i) {
        double x = points.at(i).x;
        double y = points.at(i).y;

        sum_x += x;
        sum_y += y;
        sum_xx += x * x;
        sum_xy += x * y;
        sum_yy += y * y;
        sum_xxx += x * x * x;
        sum_xxy += x * x * y;
        sum_xyy += x * y * y;
        sum_yyy += y * y * y;
    }

    double A = n * sum_xx - square(sum_x);
    double B = n * sum_xy - sum_x * sum_y;
    double C = n * sum_yy - square(sum_y);
    double D =
        0.5 * (n * sum_xyy - sum_x * sum_yy + n * sum_xxx - sum_x * sum_xx);
    double E =
        0.5 * (n * sum_xxy - sum_y * sum_xx + n * sum_yyy - sum_y * sum_yy);

    centerX = (D * C - B * E) / (A * C - square(B));
    centerY = (A * E - B * D) / (A * C - square(B));

    double sum_r = 0.0;
    for (int i = 0; i < n; ++i) {
        double x = points.at(i).x;
        double y = points.at(i).y;

        sum_r += hypot(x - centerX, y - centerY);
    }

    radius = sum_r / n;
}

std::vector<cv::Point2d> intersectCircles(double x1, double y1, double r1,
                                          double x2, double y2, double r2) {
    std::vector<cv::Point2d> ipts;

    double d = hypot(x1 - x2, y1 - y2);
    if (d > r1 + r2) {
        // circles are separate
        return ipts;
    }
    if (d < fabs(r1 - r2)) {
        // one circle is contained within the other
        return ipts;
    }

    double a = (square(r1) - square(r2) + square(d)) / (2.0 * d);
    double h = sqrt(square(r1) - square(a));

    double x3 = x1 + a * (x2 - x1) / d;
    double y3 = y1 + a * (y2 - y1) / d;

    if (h < 1e-10) {
        // two circles touch at one point
        ipts.push_back(cv::Point2d(x3, y3));
        return ipts;
    }

    ipts.push_back(cv::Point2d(x3 + h * (y2 - y1) / d, y3 - h * (x2 - x1) / d));
    ipts.push_back(cv::Point2d(x3 - h * (y2 - y1) / d, y3 + h * (x2 - x1) / d));
    return ipts;
}

char UTMLetterDesignator(double latitude) {
    // This routine determines the correct UTM letter designator for the given
    // latitude returns 'Z' if latitude is outside the UTM limits of 84N to 80S
    // Written by Chuck Gantz- chuck.gantz@globalstar.com
    char letterDesignator;

    if ((84.0 >= latitude) && (latitude >= 72.0))
        letterDesignator = 'X';
    else if ((72.0 > latitude) && (latitude >= 64.0))
        letterDesignator = 'W';
    else if ((64.0 > latitude) && (latitude >= 56.0))
        letterDesignator = 'V';
    else if ((56.0 > latitude) && (latitude >= 48.0))
        letterDesignator = 'U';
    else if ((48.0 > latitude) && (latitude >= 40.0))
        letterDesignator = 'T';
    else if ((40.0 > latitude) && (latitude >= 32.0))
        letterDesignator = 'S';
    else if ((32.0 > latitude) && (latitude >= 24.0))
        letterDesignator = 'R';
    else if ((24.0 > latitude) && (latitude >= 16.0))
        letterDesignator = 'Q';
    else if ((16.0 > latitude) && (latitude >= 8.0))
        letterDesignator = 'P';
    else if ((8.0 > latitude) && (latitude >= 0.0))
        letterDesignator = 'N';
    else if ((0.0 > latitude) && (latitude >= -8.0))
        letterDesignator = 'M';
    else if ((-8.0 > latitude) && (latitude >= -16.0))
        letterDesignator = 'L';
    else if ((-16.0 > latitude) && (latitude >= -24.0))
        letterDesignator = 'K';
    else if ((-24.0 > latitude) && (latitude >= -32.0))
        letterDesignator = 'J';
    else if ((-32.0 > latitude) && (latitude >= -40.0))
        letterDesignator = 'H';
    else if ((-40.0 > latitude) && (latitude >= -48.0))
        letterDesignator = 'G';
    else if ((-48.0 > latitude) && (latitude >= -56.0))
        letterDesignator = 'F';
    else if ((-56.0 > latitude) && (latitude >= -64.0))
        letterDesignator = 'E';
    else if ((-64.0 > latitude) && (latitude >= -72.0))
        letterDesignator = 'D';
    else if ((-72.0 > latitude) && (latitude >= -80.0))
        letterDesignator = 'C';
    else
        letterDesignator = 'Z';  // This is here as an error flag to show that
                                 // the Latitude is outside the UTM limits

    return letterDesignator;
}

void LLtoUTM(double latitude, double longitude, double& utmNorthing,
             double& utmEasting, std::string& utmZone) {
    // converts lat/long to UTM coords.  Equations from USGS Bulletin 1532
    // East Longitudes are positive, West longitudes are negative.
    // North latitudes are positive, South latitudes are negative
    // Lat and Long are in decimal degrees
    // Written by Chuck Gantz- chuck.gantz@globalstar.com

    double k0 = 0.9996;

    double LongOrigin;
    double eccPrimeSquared;
    double N, T, C, A, M;

    double LatRad = latitude * M_PI / 180.0;
    double LongRad = longitude * M_PI / 180.0;
    double LongOriginRad;

    int ZoneNumber = static_cast<int>((longitude + 180.0) / 6.0) + 1;

    if (latitude >= 56.0 && latitude < 64.0 && longitude >= 3.0 &&
        longitude < 12.0) {
        ZoneNumber = 32;
    }

    // Special zones for Svalbard
    if (latitude >= 72.0 && latitude < 84.0) {
        if (longitude >= 0.0 && longitude < 9.0)
            ZoneNumber = 31;
        else if (longitude >= 9.0 && longitude < 21.0)
            ZoneNumber = 33;
        else if (longitude >= 21.0 && longitude < 33.0)
            ZoneNumber = 35;
        else if (longitude >= 33.0 && longitude < 42.0)
            ZoneNumber = 37;
    }
    LongOrigin = static_cast<double>((ZoneNumber - 1) * 6 - 180 +
                                     3);  //+3 puts origin in middle of zone
    LongOriginRad = LongOrigin * M_PI / 180.0;

    // compute the UTM Zone from the latitude and longitude
    std::ostringstream oss;
    oss << ZoneNumber << UTMLetterDesignator(latitude);
    utmZone = oss.str();

    eccPrimeSquared = WGS84_ECCSQ / (1.0 - WGS84_ECCSQ);

    N = WGS84_A / sqrt(1.0 - WGS84_ECCSQ * sin(LatRad) * sin(LatRad));
    T = tan(LatRad) * tan(LatRad);
    C = eccPrimeSquared * cos(LatRad) * cos(LatRad);
    A = cos(LatRad) * (LongRad - LongOriginRad);

    M = WGS84_A *
        ((1.0 - WGS84_ECCSQ / 4.0 - 3.0 * WGS84_ECCSQ * WGS84_ECCSQ / 64.0 -
          5.0 * WGS84_ECCSQ * WGS84_ECCSQ * WGS84_ECCSQ / 256.0) *
             LatRad -
         (3.0 * WGS84_ECCSQ / 8.0 + 3.0 * WGS84_ECCSQ * WGS84_ECCSQ / 32.0 +
          45.0 * WGS84_ECCSQ * WGS84_ECCSQ * WGS84_ECCSQ / 1024.0) *
             sin(2.0 * LatRad) +
         (15.0 * WGS84_ECCSQ * WGS84_ECCSQ / 256.0 +
          45.0 * WGS84_ECCSQ * WGS84_ECCSQ * WGS84_ECCSQ / 1024.0) *
             sin(4.0 * LatRad) -
         (35.0 * WGS84_ECCSQ * WGS84_ECCSQ * WGS84_ECCSQ / 3072.0) *
             sin(6.0 * LatRad));

    utmEasting =
        k0 * N *
            (A + (1.0 - T + C) * A * A * A / 6.0 +
             (5.0 - 18.0 * T + T * T + 72.0 * C - 58.0 * eccPrimeSquared) * A *
                 A * A * A * A / 120.0) +
        500000.0;

    utmNorthing =
        k0 *
        (M +
         N * tan(LatRad) *
             (A * A / 2.0 +
              (5.0 - T + 9.0 * C + 4.0 * C * C) * A * A * A * A / 24.0 +
              (61.0 - 58.0 * T + T * T + 600.0 * C - 330.0 * eccPrimeSquared) *
                  A * A * A * A * A * A / 720.0));
    if (latitude < 0.0) {
        utmNorthing +=
            10000000.0;  // 10000000 meter offset for southern hemisphere
    }
}

void UTMtoLL(double utmNorthing, double utmEasting, const std::string& utmZone,
             double& latitude, double& longitude) {
    // converts UTM coords to lat/long.  Equations from USGS Bulletin 1532
    // East Longitudes are positive, West longitudes are negative.
    // North latitudes are positive, South latitudes are negative
    // Lat and Long are in decimal degrees.
    // Written by Chuck Gantz- chuck.gantz@globalstar.com

    double k0 = 0.9996;
    double eccPrimeSquared;
    double e1 =
        (1.0 - sqrt(1.0 - WGS84_ECCSQ)) / (1.0 + sqrt(1.0 - WGS84_ECCSQ));
    double N1, T1, C1, R1, D, M;
    double LongOrigin;
    double mu, phi1, phi1Rad;
    double x, y;
    int ZoneNumber;
    char ZoneLetter;
    bool NorthernHemisphere;

    x = utmEasting - 500000.0;  // remove 500,000 meter offset for longitude
    y = utmNorthing;

    std::istringstream iss(utmZone);
    iss >> ZoneNumber >> ZoneLetter;
    if ((static_cast<int>(ZoneLetter) - static_cast<int>('N')) >= 0) {
        NorthernHemisphere = true;  // point is in northern hemisphere
    } else {
        NorthernHemisphere = false;  // point is in southern hemisphere
        y -= 10000000.0;  // remove 10,000,000 meter offset used for southern
                          // hemisphere
    }

    LongOrigin = (ZoneNumber - 1.0) * 6.0 - 180.0 +
                 3.0;  //+3 puts origin in middle of zone

    eccPrimeSquared = WGS84_ECCSQ / (1.0 - WGS84_ECCSQ);

    M = y / k0;
    mu =
        M / (WGS84_A *
             (1.0 - WGS84_ECCSQ / 4.0 - 3.0 * WGS84_ECCSQ * WGS84_ECCSQ / 64.0 -
              5.0 * WGS84_ECCSQ * WGS84_ECCSQ * WGS84_ECCSQ / 256.0));

    phi1Rad = mu +
              (3.0 * e1 / 2.0 - 27.0 * e1 * e1 * e1 / 32.0) * sin(2.0 * mu) +
              (21.0 * e1 * e1 / 16.0 - 55.0 * e1 * e1 * e1 * e1 / 32.0) *
                  sin(4.0 * mu) +
              (151.0 * e1 * e1 * e1 / 96.0) * sin(6.0 * mu);
    phi1 = phi1Rad / M_PI * 180.0;

    N1 = WGS84_A / sqrt(1.0 - WGS84_ECCSQ * sin(phi1Rad) * sin(phi1Rad));
    T1 = tan(phi1Rad) * tan(phi1Rad);
    C1 = eccPrimeSquared * cos(phi1Rad) * cos(phi1Rad);
    R1 = WGS84_A * (1.0 - WGS84_ECCSQ) /
         pow(1.0 - WGS84_ECCSQ * sin(phi1Rad) * sin(phi1Rad), 1.5);
    D = x / (N1 * k0);

    latitude = phi1Rad - (N1 * tan(phi1Rad) / R1) *
                             (D * D / 2.0 -
                              (5.0 + 3.0 * T1 + 10.0 * C1 - 4.0 * C1 * C1 -
                               9.0 * eccPrimeSquared) *
                                  D * D * D * D / 24.0 +
                              (61.0 + 90.0 * T1 + 298.0 * C1 + 45.0 * T1 * T1 -
                               252.0 * eccPrimeSquared - 3.0 * C1 * C1) *
                                  D * D * D * D * D * D / 720.0);
    latitude *= 180.0 / M_PI;

    longitude = (D - (1.0 + 2.0 * T1 + C1) * D * D * D / 6.0 +
                 (5.0 - 2.0 * C1 + 28.0 * T1 - 3.0 * C1 * C1 +
                  8.0 * eccPrimeSquared + 24.0 * T1 * T1) *
                     D * D * D * D * D / 120.0) /
                cos(phi1Rad);
    longitude = LongOrigin + longitude / M_PI * 180.0;
}

long int timestampDiff(uint64_t t1, uint64_t t2) {
    if (t2 > t1) {
        uint64_t d = t2 - t1;

        if (d > std::numeric_limits<long int>::max()) {
            return std::numeric_limits<long int>::max();
        } else {
            return d;
        }
    } else {
        uint64_t d = t1 - t2;

        if (d > std::numeric_limits<long int>::max()) {
            return std::numeric_limits<long int>::min();
        } else {
            return -static_cast<long int>(d);
        }
    }
}

}  // namespace camodocal
